The degree of hydrophobicity/hydrophilicity of a micro-fluid ejection head plays an important role in the overall performance of a micro-fluid ejection device. As the size of the nozzles in nozzle plates shrinks in order to get smaller droplet sizes, the sensitivity of the fluid ejected to the surface energy of the nozzle plate increases dramatically. One factor that may effect the ejection of fluids from the nozzle plate may be the accumulation of fluid or other contaminants on the nozzle plate surface. Such accumulation of fluid on the nozzle plate may adversely affect both the size and placement accuracy of the fluid droplets ejected from the ejection head.
A temporary solution to providing a hydrophobic nozzle plate is the periodic application of an anti-wetting solvent to the nozzle plate. However the anti-wetting solvent is not permanent and must be reapplied. Accordingly, there is a need for a photodefinable nozzle plate that has suitable, substantially permanent hydrophobic characteristics and is at least as resilient as polyimide nozzle plate materials.
With regard to the foregoing, exemplary embodiments of the disclosure may provide, a nozzle plate for a micro-fluid ejection head, a method of making a hydrophobic nozzle plate, and a method for improving the resiliency of a nozzle plate. The nozzle has a photoimageable hydrophobic polycyclic polyolefin layer derived from an epoxy functionalized polynorbornene.
In another exemplary embodiment, there is provided a method for providing a hydrophobic nozzle plate for a micro-fluid ejection head. The method includes photoimaging a polycyclic polyolefin layer derived from an epoxy functionalized polynorbornene applied to a micro-fluid ejection head structure. The photoimaged layer is developed to provide nozzles therein wherein an exposed surface of the layer is essentially hydrophobic.
Yet another exemplary embodiment provides a method for improving the resiliency of a nozzle plate for a micro-fluid ejection head. The method includes photoimaging a polycyclic polyolefin layer derived from an epoxy functionalized polynorbornene applied to a micro-fluid ejection head structure. The photoimaged layer is then developed to provide nozzles therein.
Advantages of the use of the specific hydrophobic materials described herein include, but are not limited to, the fact that norbornene-based polymers have extremely high glass transition temperature (Tg) (typically >250° C.), low moisture absorption, excellent solvent resistance, good adhesion to a number of substrates, high thermal stability (5% wt. loss in a thermogravimetric analysis >300° C.), low tensile modulus, and higher elongation compared to epoxy novolac photoimageable materials. However, most notably, norbornene-based polymers typically exhibit a high degree of hydrophobicity due to their almost exclusive hydrocarbon nature. Accordingly, incorporating the norbornene-based polymers in the nozzle plate materials according to the disclosure has provided a unique solution to the wettability and resiliency problems associated with conventional photoimageable materials used for micro-fluid ejection head applications.